Pore structure of single-wall carbon nanohorn aggregates

Single-wall carbon nanohorn aggregates were characterized by N2 adsorption at 77 K and `particle densityʹ measurement using the high pressure He buoyancy method. The single-wall carbon nanohorn aggregate had micropores and its pore volume was 0.11 ml g−1. The particle density was 1.25 g ml−1. The particle density was not equal to the solid density of graphite (2.27 g ml−1), but it agreed within 15% with the density of the single-wall carbon nanohorn estimated using previous TEM data. Hence single-wall carbon nanohorns have closed micropores covered with single graphene walls. According to N2 adsorption, single-wall carbon nanohorns have a considerably large surface area (308 m2 g−1) and open microporosity which has been ascribed to the inter-particle aggregate structure, the so-called `dahlia flower type structureʹ.